In wellbores, annular barriers are used for providing zone isolation and isolation of the production zone through which the recovery of hydrocarbon takes places. The annular barriers form part of the lower casing and are submerged into the borehole by means of a drill pipe. In order to expand the expandable sleeves of the annular barriers, the drill pipe is pressurised from the top of the well, often from the rig, and all the sleeves of the annular barriers can thus be expanded or set in one operation step. Subsequently, the drill pipe is released from the lower casing, leaving the lower casing fastened in the borehole.
By conventional running tools, the disconnection mechanism is activated by rotating the drill pipe or dropping a ball into a ball seat in the running tool and then pressurising the drill pipe once more to move the seat and release the running tool from the lower casing. However, neither of these solutions is useful for providing zone isolation when using annular barriers as the expanded annular barriers must not be rotated, which will occur when rotating the drill pipe. Nor must the lower casing be pressurised to a level above that at which the annular barriers are expanded, which will occur with the solution of dropping the ball and subsequently pressurising once more.